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Full text of "Practical Organic Chemistry"

I26              PRACTICAL ORGANIC CHEMISTRY

The citraconic anhydride is now distilled in vacua and col-
lected at 110114 under a pressure of 30 mm. Yield 30  35
grams.

CH2.COOH             CH3

C(OH).COOH   =    C.CO\            + COo + 2H9O.

!                         II       \o            -

CH,.COOH              CH.CO/

Properties. Colourless liquid; b. p. 213  214 (ordinary
pressure). To convert the anhydride into citraconic acid the
calculated quantity of water is added (i mol. acid : i mol. water)?
and the mixture well stirred. The whole solidifies, on standing",
to a mass of colourless crystals of citraconic acid, which- are
dried on a porous plate ; m. p. 84 86.

MESACONIC ACID.  To a saturated solution of citraconic acicl
in ether (4 parts citraconic acid require about 5 parts of anhy-
drous ether), about I part of chloroform is added, and a few
drops of a moderately strong solution of bromine in chloroform.
The mixture is placed in strong sunlight, when mesaconic acicl,
which is insoluble in ether and chloroform, begins at once to
deposit on the side of the vessel nearest the light. Drops of
bromine are added from time to time until no further precipita-
tion occurs. The pasty mass is then filtered, washed with ether,
and dried on a porous plate. Yield 73 per cent, of the citraconic
acid ; m. p. 202. See Appendix, p. 265.

PREPARATION 38.
Urea (Carbamide),

Wohler, Pogg. Ann., 1828, 12, 253; Clemm, Annalen,  1848,
66, 382.
50 grms. potassium cyanide (9899 per cent).
140          red oxide of lead.
25           ammonium sulphate.
The potassium cyanide is heated in an iron dish over a.
large burner until it begins to fuse, when 140 grains of reel
oxide of lead are gradually added in small quantities and.
stirred in. The heat of the reaction causes the mass to melt